Gagné: Presenting the Stimulus Material

 Gagnè: il quarto evento: Presenting the Stimulus Material (1992)

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The nature of this particular event is relatively obvious. The stimuli to be displayed (or communicated) to the learner are those involved in the performance that reflects the learning. If the learner must learn a sequence of facts, such as events from historv, then there are facts that must be communicated, whether in oral or printed form. If the learner is engaged in the task of pronouncing aloud printed words, as in elementary reading, then the printed words must be displayed. If the student must learn to respond to oral questions in French, then these oral questions must be presented since they are the stimuli of the task to be learned.

Although seemingly obvious, it is nevertheless of some importance that the proper stimuli be presented as a part of the instructional events. For example, if the learner is acquiring the capability of answering questions delivered orally in French, then the proper stimuli are not English questions or printed French questions. (This is not to deny, however, that such tasks may represent subordinate skills that have previously been used as learning tasks.) If the learner is to acquire the capability of using positive and negative numbers to solve verbally stated problems, then the proper stimuli are verbally stated problems and not something else. If one neglects to use the proper stimuli for learning, the end result may be that the learner acquires the "wrong" skill.

Stimulus presentation often emphasizes features that determine selective perception.

Thus, information presented in a text may contain italics, bold print, underlining, or other kinds of physical arrangements designed to facilitate perception of essential features. When pictures or diagrams are employed, important features of the concepts they display may be heavily outlined, circled, or pointed to with arrows. In establishing discriminations, distinctive features may be emphasized by enlarging the differences between the objects to be distinguished. For example, in programs of reading readiness, large differences in shapes (such as those of a circle and triangle) may be introduced first, followed by figures exhibiting smaller differences. Distorted features of a b and d may be initially presented in order that the smaller differences of these letters will eventually be discriminated.

Stimulus presentation for the learning of concepts and rules requires the use of a variety of examples. When the objective is the learning of a concept such as circle, it is desirable to present not only large and small circles on the chalkboard or in a book, but also green circles, red ones, and ones made of rope or string.

One might even have the children stand and join hands to form a circle. For young children, the importance of this event can hardly be overemphasized.

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The failure to provide such a variety of examples accounts for the classic instance related by William James in which a boy could recognize a vertical position when a pencil was used as the test object, but not when a table knife was held in that position.

Comparable degrees of usefulness can be seen in the use of variety of examples as an event for rule learning. To apply the formula for area of a rectangle, A — x • y, the student must not only be able to recall the statement that represents the rule, but he must know that A means area; he must understand what area means; he must know the x and y are the dimensions of two nonparallel sides of the rectangle, and he must know that the dot between x and y means to multiply.

But even when all these subordinated concepts and rules are known, the learner must do a variety of examples to ensure that he understands and can use the rule. Retention and transfer are also likely to be enhanced by presenting problems stated in words, in diagrams, and in combinations of the two over a period of time.

Once such rules are learned, groups of them need to be selectively recalled, combined, and used to solve problems. Employing a variety of examples in problem solving might entail teaching the learner to break down odd-shaped figures into known shapes, like circles, triangles, and rectangles, and then to apply rules for finding the area of these figures as a way to arrive at the total area of the entire shape.

In the learning of both concepts and rules, one may proceed either inductively or deductively. In learning concrete concepts, like circle or rectangle, it is best to introduce a variety of examples before introducing the definition of the concept.

(Imagine teaching a four-year-old child the formal definition of a circle before exposure to a variety of circles!) But for older learners who are learning defined concepts, a simple definition might best come first, such as "A root is the part of a plant below the ground." Assuming the learner understands the component concepts that are contained in the statement, this should be a good start, perhaps followed at once by a picture.